The invention concerns tufting machines, and has more particular reference to cutting instrumentalities therefor.
In a tufting machine a multiplicity of yarn carrying needles arranged in side-by-side disposition upon a needle bar are caused to reciprocate relative to a backing fabric so as to pierce the same to draw yarn therethrough. At the reverse of the backing fabric each needle co-operates with a respective looper, the loopers being mounted on a common looper bar and oscillating about an axis parallel to the needle bar into or out of co-operative engagement with the respective needles to receive a loop of yarn therefrom and to retain the same on withdrawal of the needles from the backing fabric.
On a tufting machine for producing cut-pile fabrics, that is to say fabrics wherein the loops appear as pairs of single yarn elements extending from the surface of the backing fabric rather than as closed loops extending from such backing fabric, the tufting mechanism further includes a multiplicity of knives, one for each looper, whereby the loops held on the loopers are severed as they approach the back of the looper, the knives being mounted for oscillation relative to the loopers in timed relationship therewith in knife blocks adjustably mounted in a common knife bar.
In the tufting art the gauge of a pile fabric is determined by the spacing between adjacent gauge parts, i.e. the needles, loopers and knives, of the tufting machine, thus the spacing or pitch of the gauge parts is the measure of the pile fabric produced. In fine gauge fabrics, i.e. one tenth gauge or smaller, the pitch at which the gauge parts are set is 0.1 inch or smaller. As a consequence of the close spacing between adjacent gauge parts in fine gauge tufting machines difficulty has been experienced in providing arrangements wherein the spacing of the various gauge parts might be set at a requisite level and maintained at such level.